Dental composition based on silicone crosslinkable by cation process

ABSTRACT

The invention concerns dental compositions. Said composition comprises (1) a silicone crosslinkable and/or polymerizable by cation process; (2) an efficient amount of at least an initiator such as onium borate; (3) at least a photosensitizer; and (4) a dental filler present in the composition in a proportion of at least 10 wt. % relative to the composition total weight. Said dental compositions are useful for making dental prostheses or for dental restoration.

This application is a continuation of U.S. Ser. No. 11/604,510, filedNov. 27, 2006, which is a continuation of U.S. Ser. No. 10/781,064,filed Feb. 18, 2004, now U.S. Pat. No. 7,247,660, which is a divisionalof U.S. Ser. No. 09/806,6729, filed Jun. 25, 2001, now U.S. Pat. No.6,747,071, which is the U.S. National Stage of PCT/FR99/02345, filedOct. 1, 1999.

The field of the invention is that of dental compositions. Moreprecisely, the dental compositions used in the context of the presentinvention can be used for producing dental prostheses and for dentalrestoration.

Up until now, to produce dental compositions for the preparation ofdental prostheses or of dental restoration materials, it is possible touse resins based on photopolymerizable acrylates. Theseready-to-formulate products exhibit however upon use problems ofirritation and potential problems of toxicity.

In addition, these products have the major disadvantage of causing highvolume shrinkage during their polymerization, which makes their usecomplex and difficult for the production of dental prostheses or ofdental restoration materials. Problems of attachment due to the volumeshrinkage or to the lack of adherence of the polymers used are inparticular observed.

The object of the present invention is to provide novel dentalcompositions which do not exhibit the disadvantages of the prior art.These novel dental

compositions, which are polymerizable and/or crosslinkable in an oralenvironment, have markedly improved qualities, in particular as regardsthe very marked reduction in the phenomenon of shrinkage of the dentalcompositions used for the production of dental prostheses or of dentalrestoration materials.

-   -   The polymerizable and/or crosslinkable dental composition        according to the invention comprises:    -   (1) at least one crosslinkable and/or polymerizable silicone        oligomer or polymer which is liquid at room temperature or which        is heat-meltable at a temperature of less than 100° C., and        which comprises:        -   at least one unit of formula (FS):

Z—Si—(R⁰ _(a))—O_((3-a)/2)

-   -   in which:        -   a=0, 1 or 2,        -   R^(o), identical or different, represents an alkyl,            cycloalkyl, aryl, vinyl, hydrogeno or alkoxy radical,            preferably a C₁-C₆ lower alkyl,        -   Z, identical or different, is an organic substituent            comprising at least one reactive epoxy, and/or alkenyl ether            and/or oxetane and/or dioxolane and/or carbonate functional            group, and preferably Z being an organic substituent            comprising at least one reactive epoxy and/or dioxolane            functional group,        -   and at least two silicon atoms,    -   (2) an effective quantity of at least one borate-type        photoinitiator,    -   (3) at least one aromatic hydrocarbon photosensitizer with one        or more aromatic nuclei which are substituted or not, having a        residual light absorption of between 200 and 500 nm,    -   (4) and at least one dental filler present in a proportion of at        least 10% by weight relative to the total weight of the        composition.

According to a first advantageous variant of the present invention, thedental composition is polymerizable and/or crosslinkable underactivation by the thermal route and/or by the photochemical route.

In general, the photochemical activation is carried out under UVradiation. More particularly, UV radiation having a wavelength of theorder of 200 to 500 nm is used for the production of dental prosthesesand UV-visible radiation having a wavelength greater than 400 nm for theproduction of restoration materials, A wavelength greater than 400 nmallows crosslinking and/or polymerization in an oral environment.

The silicone polymer or oligomer (1) has the advantage, compared withorganic resins which are crosslinked by the cationic route, of beingtransparent to UV-visible light and therefore its use makes it possibleto obtain materials which are very thick and whose photocrosslinkingoccurs in a short time.

The reactive functional groups Z of the silicone polymer or oligomer (1)may be highly varied. However, particularly advantageous dentalcompositions are obtained when the silicone oligomer or polymer (1)comprises at least one (FS) unit in which Z represents an organicsubstituent Z1 comprising at least one reactive epoxy, and/or dioxolanefunctional group, and preferably at least one reactive epoxy functionalgroup.

According to two advantageous alternatives of the present invention, thesilicone oligomer or polymer (1) with at least one reactive epoxy and/ordioxolane functional group Z1, and preferably at least one reactiveepoxy functional group may:

-   -   (i) either comprise only this (these) type(s) of reactive        functional group(s) Z1,    -   (ii) or comprise other reactive functional groups Z such as the        reactive alkenyl ether, oxetane and/or carbonate functional        groups Z2.

In the case of the first alternative (i), the dental composition mayalso comprise other silicone oligomers and/or polymers comprising otherreactive functional groups Z2 such as alkenyl ether, oxetane and/orcarbonate functional groups and optionally reactive functional groupsZ1.

By way of examples of reactive functional groups Z, these may inparticular be chosen from the following radicals:

—(CH₂)₃—O—CH═CH₂;

—(CH₂)₃—O—CH═CH—R″

-   -   with R″ representing a linear or branched C₁-C₆ alkyl radical.

According to a second advantageous variant of the present invention, thesilicone polymer or oligomer consists of at least one silicone havingthe following average formula:

The cationic photoinitiators are chosen from onium borates (taken ontheir own or as a mixture with each other) of an element of groups 15 to17 of the Periodic Table [Chem. & Eng. News, vol. 63, No. 5, 26 of 4Feb. 1985] or of an organometallic complex of an element of groups 4 to10 of the Periodic Table [same reference].

The cationic entity of the borate is selected from:

-   -   (1) the onium salts of formula (I)

[(R¹)_(n)-A-(R²)_(m)]⁺  (I)

-   -   in which formula:        -   A represents an element of groups 15 to 17 such as for            example: I, S, Se, P or N,        -   R¹ represents a carbocyclic or heterocyclic C₆-C₂₀ aryl            radical, it being possible for said heterocyclic radical to            contain, as heteroelements, nitrogen or sulfur,        -   R² represents R¹ or a linear or branched C₁-C₃₀ alkyl or            alkenyl radical; said radicals R¹ and R² being optionally            substituted with a C₁-C₂₅ alkoxy, C₁-C₂₅ alkyl, nitro,            chloro, bromo, cyano, carboxyl, ester or mercapto group,        -   n is an integer ranging from 1 to v+1, v being the valency            of the element A,        -   m is an integer ranging from 0 to v−1 with n+m=v+1,    -   (2) the oxoisothiochromanium salts described in patent        application WO 90/11303, in particular the sulfonium salt of        2-ethyl-4-oxoisothiochromanium or        2-dodecyl-4-oxoisothiochromanium,    -   (3) the sulfonium salts in which the cationic entity comprises:        -   3₁ at least one polysulfonium entity of formula (II.1):

in which:

the symbols Ar¹, which are identical or different, each represent amonovalent phenyl or naphthyl radical, optionally substituted with oneor more radicals chosen from: a linear or branched C₁-C₁₂, preferablyC₁-C₆, alkyl radical, a linear or branched C₁-C₁₂, preferably C₁-C₆,alkoxy radical, a halogen atom, an —OH group, a —COOH group, an estergroup —COO-alkyl, where the alkyl portion is a linear or branchedC₁-C₁₂, preferably C₁-C₆, residue, and a group of formula —Y⁴—Ar² wherethe symbols Y⁴ and Ar² have the meanings given just below,

the symbols Ar², which are identical or different, each represent amonovalent phenyl or naphthyl radical, optionally substituted with oneor more radicals chosen from: a linear or branched C₁-C₁₂, preferablyC₁-C₆, alkyl radical, a linear or branched C₁-C₁₂, preferably C₁-C₆,alkoxy radical, a halogen atom, an —OH group, a —COOH group, an estergroup —COO-alkyl where the alkyl portion is a linear or branched C₁-C₁₂,preferably C₁-C₆, residue,

the symbols Ar³, which are identical or different, each represent adivalent phenylene or naphthylene radical, optionally substituted withone or more radicals chosen from: a linear or branched C₁-C₁₂,preferably C₁-C₆, alkyl radical, a linear or branched C₁-C₁₂, preferablyC₁-C₆, alkoxy radical, a halogen atom, an —OH group, a —COOH group, anester group —COO-alkyl where the alkyl portion is a linear or branchedC₁-C₁₂, preferably C₁-C₆, residue,

t is an integer equal to 0 or 1, with the additional conditionsaccording to which:

-   -   + when t=0, the symbol Y is then a monovalent radical Y¹        representing the group of formula:

-   -   where the symbols Ar¹ and Ar² possess the meanings given above,    -   + when t=1:    -   on the one hand, the symbol Y is then a divalent radical having        the following meanings Y² to Y⁴:        -   Y²: a group of formula:

-   -   where the symbol Ar² has the meanings given above,        -   Y³: a single valency bond,        -   Y⁴: a divalent residue chosen from:

-   -   a linear or branched C₁-C₁₂, preferably C₁-C₆, alkylene residue        and a residue of formula —Si(CH₃)₂O—,    -   on the other hand, in the case solely where the symbol Y        represents Y³ or Y⁴, the (terminal) radicals Ar¹ and Ar²        possess, in addition to the meanings given above, the        possibility of being linked to each other by the residue Y′        consisting of Y′¹ a single valency bond or of Y′² a divalent        residue chosen from the residues cited in relation to the        definition of Y⁴, which is inserted between the carbon atoms,        opposite each other, situated on each aromatic ring at the ortho        position with respect to the carbon atom directly linked to the        cation S⁺;

3₂ and/or at least one monosulfonium entity possessing a single cationiccenter S⁺ per mol of cation and consisting, in most cases, of entity offormula (II.2):

in which Ar¹ and Ar² have the meanings given above in relation toformula (III.1), including the possibility of directly linking to eachother only one of the radicals Ar¹ to Ar² in the manner indicated abovein relation to the definition of the additional condition in force whent=1 in formula (II), calling into play the residue Y′;(4) the organometallic salts of formula (III):

(L¹L²L³M)^(+q)

in which formula:

-   -   M represents a group 4 to 10 metal, in particular iron,        manganese, chromium or cobalt,

L¹ represents 1 ligand bound to the metal M by π electrons, which ligandis chosen from the ligands η³-alkyl, η⁵-cyclopendadienyl andη⁷-cycloheptratrienyl and the η⁶-aromatic compounds chosen from theoptionally substituted η⁶-benzene ligands and the compounds having from2 to 4 condensed rings, each ring being capable of contributing to thevalency layer of the metal M by 3 to 8 π electrons;

L² represents a ligand bound to the metal M by π electrons, which ligandis chosen from the ligands η⁷-cycloheptratrienyl and the η⁶-aromaticcompounds chosen from the optionally substituted ligands η⁶-benzene andthe compounds having from 2 to 4 condensed rings, each ring beingcapable of contributing to the valency layer of the metal M by 6 or 7 πelectrons;

L³ represents from 0 to 3 ligands, which are identical or different,linked to the metal M by σ electrons, which ligand(s) is (are) chosenfrom CO and NO₂ ⁺; the total electron charge q of the complex to whichL¹, L² and L³ contribute and the ionic charge of the metal M beingpositive and equal to 1 or 2;

The anionic borate entity has the formula [BX_(a)R_(b)]⁻ in which:

a and b are integers ranging, for a, from 0 to 3 and for b, from 1 to 4with a+b=4,

the symbols X represent:

a halogen atom (chlorine, fluorine) with a ═0 to 3,

an OH functional group with a ═0 to 2,

the symbols R are identical or different and represent:

-   -   a phenyl radical substituted with at least one        electron-attracting group such as for example OCF₃, CF₃, NO₂,        CN, and/or with at least 2 halogen atoms (fluorine most        particularly), this being when the cationic entity is an onium        of an element of groups 15 to 17,    -   a phenyl radical substituted with at least one element or one        electron-attracting group, in particular a halogen atom        (fluorine most particularly), CF₃, OCF₃, NO₂, CN, this being        when the cationic entity is an organometallic complex of an        element of groups 4 to 10,    -   an aryl radical containing at least two aromatic nuclei such as        for example biphenyl, naphthyl, optionally substituted with at        least one electron-attracting group or element, in particular a        halogen atom (fluorine most particularly), OCF₃, CF₃, NO₂, CN,        regardless of the cationic entity.

Without being limiting, more details are given below as regards thesubclasses of onium borate and of borate of organometallic salts moreparticularly preferred in the context of the use in accordance with theinvention.

According to a first preferred variant of the invention, the entity ofthe anionic borate entity which are most particularly suitable are thefollowing:

-   -   1′: [B(C₆F₅)₄]⁻    -   2′: [(C₆F₅)₂BF₂]⁻    -   3′: [B(C₆H₄CF₃)₄]⁻    -   4′: [B(C₆F₄OCF₃)₄]³¹.    -   5′: [B(C₆H₃(CF₃)₂)₄]⁻    -   6′: [B(C₆H₃F₂)₄]⁻    -   7′: [C₆F₅BF₃]⁻

According to a second preferred variant of the invention, the oniumsalts (1) which can be used are described in numerous documents, inparticular in U.S. Pat. No. 4,026,705, U.S. Pat. No. 4,032,673, U.S.Pat. No. 4,069,056, U.S. Pat. No. 4,136,102, U.S. Pat. No. 4,173,476.Among these, the following cations will be most particularly preferred:

-   -   [(φ)₂I]⁺    -   [C₈H₁₇-O-φ-I-φ]⁺    -   [(φ-CH₃)₂ I]⁺    -   [C₁₂H₂₅-φ-I-φ]⁺    -   [(C₈H₁₇-O-φ)₂ I]⁺    -   [(C₈H₁₇-O-φ-I-φ)]⁺    -   [(φ)₃ S]⁺    -   [(φ)₂-S-φ-O-C₈H₁₇]³⁰ [(CH₃-φ-I-φ-CH(CH₃)₂]⁺    -   [φ-S-φ-S-(φ)₂]⁺    -   [(C₁₂H₂₅-φ)₂ I]⁺    -   [(CH₃-φ-I-φ-OC₂H₅]⁺

According to a third preferred variant, the organometallic salts (4)which can be used are described in the documents U.S. Pat. No.4,973,722, U.S. Pat. No. 4,992,572, EP-A-203 829, EP-A-323 584 andEP-A-354 181. The organometallic salts most readily selected accordingto the invention are in particular:

-   -   (η⁵-cyclopentadienyl)(η⁶-toluene) Fe⁺,    -   (η⁵-cyclopentadienyl)(η⁶-methyl-1-naphthalene) Fe⁺,    -   (η⁵-cyclopentadienyl)(η⁶-cumene) Fe⁺,    -   bis(η⁶-mesitylene) Fe⁺,    -   bis(η⁶-benzene) Cr⁺.

In agreement with these three preferred variants, the following productsmay be mentioned by way of examples of photoinitiators of the oniumborate type:

-   -   [(φ)₂ I]⁺, [B(C₆F₅)₄]⁻    -   [(C₈H₁₇)-O-φ-I-φ)]⁺, [B(C₆F₅)₄]⁻    -   [C₁₂H₂₅-φ-I-φ]⁺, [B(C₆F₅)₄]⁻    -   [(C₈H₁₇-O-φ)₂I]⁺, [B(C₆F₅)₄]⁻    -   [(C₈H₁₇)-O-φ-I-φ)]⁺, [B(C₆F₅)₄]⁻    -   [(φ)₃S]⁺, [B(C₆F₅)₄]⁻    -   [(φ)₂S-φ-O-C₈H₁₇]⁺, [B(C₆H₄CF₃)₄]⁻[(C₁₂H₂₅-φ)₂I]^(+, [B(C)        ₆F₅)₄]⁻    -   [(φ)₃ S]⁺, [B(C₆F₄OCF₃)₄]⁻    -   [(φ-CH₃)₂I]⁺, [B(C₆F₅)₄]⁻    -   [(φ-CH₃)₂ I]⁺, [B(C₆F₄OCF₃)₄]⁻    -   [CH₃-φ-I-φCH(CH₃)₂]^(−, [B(C) ₆F₅)₄]⁻    -   (η⁵-cyclopentadienyl)(η⁶-toluene) Fe⁺, [B(C₆F₅)₄]⁻    -   (η⁵-cyclopentadienyl)(η⁶-methyl-1-naphthalene) Fe⁺, [B(C₆F₅)₄]⁻    -   (η⁵-cyclopentadienyl)(η⁶-cumene) Fe⁺, [B(C₆F₅)₄]⁻

As another literary reference for defining the onium borates (1) and (2)and the borates of organometallic salts (4), there may be mentioned theentire content of patent applications EP 0 562 897 and 0 562 922. Thiscontent is integrally incorporated by reference into the presentdisclosure.

As another example of onium salt which can be used as photoinitiator,there may be mentioned those disclosed in U.S. Pat. No. 4,138,255 andU.S. Pat. No. 4,310,469.

Other cationic photoinitiators may also be used, e.g.:

-   -   those marketed by Union-Carbide (photoinitiator 6990 and 6974        triarylsulfonium hexafluorophosphate and hexafluoroantimonate),    -   the salts of iodonium hexafluorophosphate or        hexafluoroantimonate,    -   or the ferrocenium salts of these various anions.

The nature of the photosensitizer contained in the dental compositionaccording to the invention may be highly varied. In the context of theinvention, it corresponds in particular to one of the following formulae(IV) to (XXII):

in which:

-   -   when n=1, Ar¹ represents an aryl radical containing from 6 to 18        carbon atoms, a tetrahydronaphthyl, thienyl, pyridyl or furyl        radical or a phenyl radical carrying one or more substituents        chosen from the group consisting of F, Cl, Br, CN, OH, linear or        branched C₁-C₁₂ alkyls, —CF³, —OR⁶, —OPhenyl, —SR⁶, —SPhenyl,        —SO₂Phenyl, —COOR⁶, —O—(CH₂—CH═CH₂), —O(CH₂H₄—O)_(m)—H,        —O(C₃H₆O)_(m)—H, m being between 1 and 100,    -   when n=2, Ar₁ represents a C₆-C₁₂ arylene radical or a        phenylene-T-phenylene radical where T represents —O—, —S—, —SO₂—        or —CH₂—,    -   X represents a group —OR⁷ or —OSiR⁸(R⁹)₂ or forms, with R⁴, a        group —O—CH(R¹⁰)—,    -   R₄ represents a linear or branched C₁-C₈ alkyl radical which is        unsubstituted or which carries an —OH, —OR⁶, C₂-C₈ acyloxy, —CF³        or —CN group, a C₃ or C₄ alkenyl radical, a C₆ to C₁₈ aryl        radical, a C₇ to C₉ phenylalkyl radical,    -   R⁵ has one of the meanings given for R⁴ or represents a radical        —CH₂CH₂R¹¹, or alternatively forms with R⁴ a C₂-C₈ alkylene        radical or a C₃-C₉ oxa-alkylene or aza-alkylene radical,    -   R⁶ represents a lower alkyl radical containing from 1 to 12        carbon atoms,    -   R⁷ represents a hydrogen atom, a C₁-C₁₂ alkyl radical, a C₂-C₆        alkyl radical carrying an —OH, —OR⁶ or —CN group, a C₃-C₆        alkenyl radical, a cyclohexyl or benzyl radical, a phenyl        radical optionally substituted with a chlorine atom or a linear        or branched C₁-C₁₂ alkyl radical, or a 2-tetrahydropyranyl        radical,    -   R⁸ and R⁹ are identical or different and each represent a C₁-C₄        alkyl radical or a phenyl radical,    -   R¹⁰ represents a hydrogen atom, a C₁-C₈ alkyl radical or a        phenyl radical,    -   R¹¹ represents a radical —CONH₂, —CONHR⁶, —CON(R⁶)₂, —P(O)        (OR⁶)₂ or 2-pyridyl;

in which:

-   -   Ar² has the same meaning as Ar¹ of formula (IV) in the case        where n=1,    -   R¹⁵ represents a radical chosen from the group consisting of a        radical Ar², a linear or branched C₁-C₁₂ alkyl radical, a C₆-C₁₂        cycloalkyl radical, and a cycloalkyl radical forming a C₆-C₁₂        ring with the carbon of the ketone or a carbon of the radical        Ar², it being possible for these radicals to be substituted with        one or more substituents chosen from the group consisting of —F,        —Cl, —Br, —CN, —OH, —CF₃, —OR⁶, —SR⁶, —COOR⁶, the linear or        branched C₁-C₁₂ alkyl radicals optionally carrying an —OH, —OR⁶        and/or —CN group, and the linear or branched C₁-C₈ alkenyl        radicals;

in which:

-   -   Ar³ has the same meaning as Ar¹ of formula (IV) in the case        where n=1,        -   R¹⁶, identical or different, represents a radical chosen            from the group consisting of a radical Ar³, a radical            —(C═O)—Ar³, a linear or branched C₁-C₁₂ alkyl radical, a            C₆-C₁₂ cycloalkyl radical, it being possible for these            radicals to be substituted with one or more substituents            chosen from the group consisting of —F, —Cl, —Br, —CN, —OH,            —CF₃, —OR⁶, —SR⁶, —COOR⁶, the linear or branched C₁-C₁₂            alkyl radicals optionally carrying an —OH, —OR⁶ and/or —CN            group, and the linear or branched C₁-C₈ alkenyl radicals;

in which:

-   -   R⁵, which are identical or different, have the same meanings as        in formula (III),    -   Y, which are identical or different, represent X and/or R⁴,    -   Z represents:    -   a direct bond,    -   a C₁-C₆ divalent alkylene radical, or a phenylene, diphenylene        or phenylene-T-phenylene radical, or alternatively forms, with        the two substituents R⁵ and the two carbon atoms carrying these        substituents, a cyclopentane or cyclohexane nucleus,    -   a divalent group —O—R¹²—O—, —O—SiR⁸R⁹—O—SiR⁸R⁹—O—, or        —O—SiR⁸R⁹—O—,    -   R¹² represents a C₂-C₈ alkylene, C₄-C₆ alkenylene or xylylene        radical,    -   and Ar⁴ has the same meaning as Ar¹ of formula (IV) in the case        where n=1.    -   family of thioxanthones of formula (VIII):

—R¹⁷, identical or different substituent(s) on the aromatic nucleus(nuclei), represent a linear or branched C1-C12 alkyl radical, a C6-C12cycloalkyl radical, a radical Ar¹, a halogen atom, an —OH, —CN, —NO₂,—COOR⁶, —CHO, Ophenyl, —CF₃, —SR⁶, -Sphenyl, —SO₂phenyl, Oalkenyl, or—SiR⁶ ₃ group.

family of xanthenes of formula (IX):

family of xanthones of formula (X):

family of the naphthalene of formula (XI):

family of the anthracene of formula (XII):

family of the phenanthrene of formula (XIII):

for example 2,7-dinitro-9-fluorenone,

family of the chromone of formula (XIX):

family of the eosin of formula (XX):

family of the erythrosin of formula (Ma):

family of the biscoumarins of formula (XXII):

R¹⁸, identical or different, has the same meaning as R¹⁷ or represents agroup —NR⁶ ₂, for example 3,3′-carbonylbis(7-diethylaminocoumarin) and3,3′-carbonyl-bis(7-methoxycoumarin).

Other sensitizers can be used. In particular, the photosensitizersdescribed in the documents U.S. Pat. No. 4,939,069; U.S. Pat. No.4,278,751; U.S. Pat. No. 4,147,552 may be used.

In the context of the present invention, the photosensitizers have aresidual absorption of UV light between 200 and 500 nm, preferably 400to 500 nm for the preparations of dental prostheses. For dentalrestoration, a photosensitizer having a residual absorption of UV lightabove 400 nm will be preferred.

According to a preferred variant, the photosensitizers will be chosenfrom those of the families (IV), (VII) and (VIII). By way of examples,the following photosensitizers will be mentioned:

4,4′-dimethoxybenzoin; 2-4-diethylthioxanthone 2-ethylanthraquinone;2-methylanthraquinone; 1,8-dihydroxyanthraquinone; dibenzoylperoxide;2,2-dimethoxy-2- benzoin; phenylacetophenone; 2-hydroxy-2- benzaldehyde;methylpropiophenone; 4-(2-hydroxyethoxy) phenyl-(2-hydroxy-2-methylpropyl)-ketone; benzoylacetone;

2-isopropylthioxanthone; 1-chloro-4-propoxy- thioxanthone;4-isopropylthioxanthone; and the mixture thereof.

Various types of fillers can be used for preparing the compositionsaccording to the invention. The fillers are chosen according to thefinal use of the dental composition: these affect important propertiessuch as appearance, penetration of UV radiation, as well as themechanical and physical properties of the material obtained aftercrosslinking and/or polymerization of the dental composition.

As reinforcing filler, there may be used treated or untreated pyrogenicsilica fillers, amorphous silica fillers, quartz, glass or nonglassyfillers based on oxides of zirconium, barium, calcium, fluorine,aluminum, titanium, zinc, borosilicates, aluminosilicates, talc,spherosil, ytterbium trifluoride, fillers based on polymers in groundpowder form, such as inert or functionalized methyl polymethacrylates,polyepoxides or polycarbonates.

By way of example, there may be mentioned:

-   -   inert fillers based on methyl polymethacrylate LUXASELF from the        company UGL, which can be used in the dental field and which are        pigmented in pink,    -   hexamethyldisilazane-treated fumed silica fillers having a        specific surface area of 200 m²/g,    -   untreated fumed silica fillers (“aerosil” AE200 marketed by        DEGUSSA).

According to an advantageous variant of the invention, the fillers andin particular the silica fillers are treated before use at 120° C. witha quantity of less than 10% w/w of silicone comprising at least one unitof formula (XXIII):

-   -   such that Z′ has the same definition as Z−a=0, 1, 2 or 3    -   with at least one silicon atom.

There may be mentioned by way of example the polymer described belowwith Z=epoxide and Z=trialkoxysilyl

In this case for the treatment of silicone-containing filler(s), inparticular silica, with this type of polymer, the material obtainedafter crosslinking has a mechanical strength, a modulus of elasticityand a resistance to compression which are markedly improved.

In addition to the reinforcing fillers, pigments may be used to colorthe dental composition according to the invention envisaged and theethnic groups.

For example, red pigments are used in the presence of microfibers forthe dental compositions used for the preparation of dental prostheses inorder to simulate the blood vessels.

Pigments based on metal oxides (iron and/or titanium and/or aluminumand/or zirconium oxides, and the like) are also used for the dentalcompositions used for the preparation of restoration material, in orderto obtain a crosslinked material having an ivory color.

Other additives may be incorporated into the dental compositionsaccording to the invention. For example, biocides, stabilizers,flavoring agents, plasticizers and adherence promoters.

Among the additives which may be envisaged, there will be advantageouslyused crosslinkable and/or polymerizable coreagents of the organic type.These coreagents are liquid at room temperature or are hot-meltable at atemperature of less than 100° C., and each coreagent comprises at leasttwo reactive functional groups such as oxetane-alkoxy, oxetane-hydroxyl,oxetane-alkoxysilyl, carboxyl-oxetane, oxetane-oxetane, alkenylether-hydroxyl, alkenyl ether-alkoxysilyl, epoxy-alkoxy,epoxy-alkoxysilyls, dioxolane-dioxolane-alcohol, and the like.

The dental compositions according to the invention may be used fornumerous dental applications, and in particular in the field of dentalprostheses, in the field of dental restoration and in the field oftemporary teeth.

The dental composition according to the invention is preferably providedin the form of a single product containing the various components)(“monocomponent”) which facilitates its use, in particular in the fieldof dental prostheses. Optionally, the stability of this product may beprovided for by organic derivatives with amine functional groupsaccording to the teaching of the document WO 98/07798.

In the field of dental prostheses, the product in the “monocomponent”form may be deposited with the aid of a syringe directly on the plastermodel or in a core. Next, it is polymerized (polymerization by possiblesuccessive layers) with the aid of a UV lamp (visible light spectrum200-500 nm).

In general, it is possible to produce a lasting and esthetic dentalprosthesis in 10 to 15 min.

It should be noted that the products obtained from the dentalcomposition according to the invention are nonporous. Thus, after anoptional polishing with the aid of a felt brush, for example, thesurface of the dental prostheses obtained is smooth and bright andtherefore does not require the use of varnish.

The applications in the field of dental prostheses are essentially thoseof the joined prosthesis, which can be divided into two types:

-   -   full prosthesis in the case of a patient with absolutely no        teeth    -   partial prosthesis due to the absence of several teeth,        resulting either in a provisional prosthesis, or a skeleton        brace.

In the field of dental restoration, the dental composition according tothe invention may be used as material for filling the anterior andposterior teeth in different colors (for example “VITA” colors), whichis rapid and easy to use.

The dental composition being nontoxic and polymerizable in thick layers,it is not essential to polymerize the material in successive layers. Ingeneral, a single injection of the dental composition is sufficient.

The preparations for dental prostheses and for restoration materials arecarried out according to techniques which are customary in the art.

In the case of application of the dental composition as a tooth, eitherthe tooth may be pretreated with a bonding primer or the dentalcomposition may be prepared as a mixture with a bonding primer beforeits use. However; it is not essential to use a bonding primer in orderto use the dental composition according to the invention.

The following examples and tests are given by way of illustration. Theymake it possible in particular to understand more clearly the inventionand to highlight some of its advantages and to illustrate a few of itsvariant embodiments.

EXAMPLES AND TESTS

The product used in the compositions of the examples are the following:

product (A):

Product (2): this product is a mixture of siloxanes, whose viscosity is23.5 mPa·s and in which the proportions by weight and formulae B₁, B₂and B₃ are given below:

with 89% of B₁ where a=0, 9% of B₁ where a=1; 0.2% of B₁ where a=2;

with 0.3% of B2 where a=0;

and with 1.5% of B3 where a=0 and b=1.

product (P1):

Product (PS1): isopropylthioxanthone marketed under the trademarkQuantacure ITX by the company RAHN.

EXAMPLE 1 Composition for Dental Prosthesis

The following are mixed using a three-blade stirrer:

-   -   100 parts of siloxane (A) stabilized with 50 ppm of Tinuvin 765;    -   1 part of photoinitiator (P1) at 75% in ethyl acetate;    -   0.028 part of photosensitizer (PS1);    -   150 parts of a pink-pigmented, polymethyl methacrylate-based        inert filler (product LUXASELF from UGL dentaire).

The composition obtained is perfectly stable in the absence of light forseveral months at room temperature. This composition can be workedmanually and for several hours in the presence of daylight.

A test piece 2.8±0.3 mm thick is prepared in a glass dish 64 mm long(model), 10 mm wide (model) and open at the top by pouring the preparedcomposition (“monocomponent”) into the dish.

The composition is dried by passing the dish for 1 to 2 seconds (3m/min) under a UV lamp of 200 W/cm power corresponding to the excitationof a mixture of mercury and gallium and emitting in the UV-visible rangeabove 400 nm.

The product obtained is unmolded by breaking the glass.

The SHORE D hardness of the two polymerized compositions is determinedon each side of the item made immediately after crosslinking.

Immediate Measurement Example 1 measurement after 10 hours Irradiatedsurface: 70 85 Bottom surface 60 85

The Shore D hardness continues to change substantially over a few hours.

The volume shrinkage is very low and excellent size stability isobtained.

The loss of mass is less than 1%.

The product may be used with or without bonding primer in the presenceof artificial teeth or of natural teeth.

More generally, the properties of the material obtained are in agreementwith the DIN/ISO 1567 standard.

EXAMPLE 2 Composition for Dental Restoration

A composition for dental restoration is prepared by mixing:

-   -   200 parts of siloxane (A) stabilized with 50 ppm of Tinuvin 765;    -   1.8 parts of photoinitiator (P1) at 75% in ethyl acetate;    -   0.0178 part of photosensitizer (PS1);    -   52 parts of hexamethyldisilazane-treated fumed silica having a        specific surface area of 200 m²/g;    -   20 parts of untreated amorphous silica dried for 4 hours at        200° C. before formulation.

A flowing composition is obtained which has a translucent grayappearance.

The crosslinking-polymerization operation is carried out using a lampemitting alight spot emitted through a curved light tip 8 mm indiameter. The source is an Optibulb 80 W lamp (DEMETRON Optilux 500) forwavelengths of between 400 and 520 nm.

The dental composition is applied in a tooth. A thickness of 5 mm iscrosslinked in less than 30 seconds.

A SHORE D hardness of 50 is obtained immediately and can reach 80 to 100within a few hours.

No loss is observed in size stability. The porosity of the crosslinkedmaterial, based on observation of a section under a microscope, is zero.

The color of the composite after crosslinking is close to ivory color.

EXAMPLE 3 Composition for Dental Restoration

The same concentrations of components and the same procedure as above inExample 2 are used.

However, the mixture of fillers is treated, before use, at 120° C. with5% w/w of silicone of average general formula containing less than 50ppm of residual platinum:

The restoration material obtained after crosslinking according to theprocedure of Example 2 has a better mechanical strength, an improvedmodulus of elasticity and a better compression resistance.

A SHORE D hardness of 80 is obtained immediately.

The size stability and the porosity properties of the material areexcellent.

EXAMPLE 4 Dental Precomposition

A dental precomposition, prepared without fillers, is obtained by mixingusing a magnetic stirrer bar:

-   -   1 part of siloxane (A) having a density of 0.997, stabilized        with 50 ppm of Tinuvin 765,    -   0.01 part of photoinitiator (P1) at 10% in solution, dissolved        directly in siloxane A,    -   0.00028 part of photosensitizer (PS1) contained in the        photoinitiator (P1).

The crosslinking operation is carried out in a manner identical to thatof Example 2. A composition 5 mm thick is crosslinked in less than 30seconds.

The density of the crosslinked composition is measured using a brasspycnometer and its value is 1.0274. The volume shrinkage is therefore3.05% [=(1.0274−0.997)/0.997×100] in the absence of fillers.Consequently, a dental composition of this type, formulated with morethan 50% of filler, will have a very low volume shrinkage which is lessthan 1.5%.

EXAMPLE 5 Dental Precomposition

(a) A dental precomposition prepared without fillers is obtained bymixing using a three-blade stirrer,

-   -   10 parts of siloxane (A) having a density of 0.997, stabilized        with 50 ppm of Tinuvin 765,    -   0.01 part of photoinitiator (P1) dissolved directly in silicone        (A),    -   and 62 ppm of photosensitizer (PS1) contained in the        photoinitiator.

Eight grams of this dental precomposition are then placed in an opencylindrical aluminum cup in a manner such that the volume occupiedrepresents a thickness of about 6 mm.

The liquid is photocrosslinked by passing the cup under a UV lampdelivering, through a pane of glass 6 mm thick, UV-V (>390 nm)=0.6W/cm². The UV-V (>390 nm) dose received is 0.4 J/cm² at 10 m/min.

The degree of conversion of the epoxy functional groups immediatelyafter polymerization is measured from the residual heat of reactionrecorded by differential calorimetry. The residual heat is 17 J/grelative to a noncrosslinked sample which represents 237 J/g. Theeffective degree of conversion of the epoxy functional groups with 0.1%photoinitiator is therefore 93%.

(b) The same composition as above in (a) is prepared by adding 5% w/w of3-ethyl-3-(hydroxymethyl)oxetane during the preparation of thecomposition. The composition is then crosslinked in the same manner asabove in (a).

The degree of conversion of the epoxy functional groups is 99.3% with aresidual heat of 1.5 J/g.

(c) The same composition as above in (a) is prepared by adding 10% w/wof 3-ethyl-3-(hydroxymethyl)oxetane during the preparation of thecomposition. The composition is then crosslinked in the same manner asabove in (a).

The degree of conversion of the epoxy functional groups is 99.95% with aresidual heat of 0.1 J/g.

EXAMPLE 6 Composition for Dental Prosthesis or Dental RestorationMaterial

The following are mixed using a three-blade stirrer:

-   -   95 parts of siloxane (A) stabilized with 50 ppm of Tinuvin 765,    -   62 ppm of photosensitizer (PS1),    -   0.5 part of photoinitiator (P1) at 10% in siloxane (A),    -   5 parts of 3-ethyl-3-(hydroxymethyl)-oxetane,    -   and 120 parts of precipitated silica (ground quartz).

A dental composition is obtained with is opaque, gray in color,nonflowing and easy to handle.

The crosslinking operation is carried out in a manner identical to thatof Example 2. A composition 5 mm thick crosslinks in less than 30seconds.

The color of the material after crosslinking is close to ivory color.

The material is suitable in particular for dental prosthesis use, inparticular the stiffness is greater than 80 Mpa according to the ISO1567 standard.

EXAMPLE 7 Dental Composition

This composition is formulated with:

-   -   95 parts of silicone (B),    -   62 ppm of photosensitizer (PS1),    -   0.5 part of photoinitiator (P1) at 10% in siloxane (B),    -   5 parts of the oxetane 3-ethyl-3-(hydroxymethyl)oxetane,    -   and 120 parts of precipitated silica (ground quartz).

The crosslinking operation is carried out in a manner identical to thatof Example 2.

The stiffness values found are greater than 80 Mpa according to the ISO1567 standard.

EXAMPLE 8 Dental Precomposition

A dental precomposition M1 prepared without fillers is obtained bymixing using a three-blade stirrer:

-   -   100 parts of a silicone composition (B) having a density of        0.997 and stabilized with 50 ppm of Tinuvin 765,    -   0.1 part of photoinitiator (P1) at 10% in solution, dissolved        directly in silicone (B),    -   and 0.028 part of photosensitizer (PS1).

A portion of the composition obtained M1 is removed so as to crosslinkit. The crosslinking operation is carried out in a manner identical tothat of Example 2. A composition 5 mm thick crosslinks in less than 30seconds.

The density of the crosslinked material, measured using a brasspycnometer, is 1.0274. The volume shrinkage is therefore 3.05%[=(1.0274-0.997)/0.997×100] in the absence of fillers. Consequently, adental composition of this type, formulated with more than 50% offillers, will have a very low volume shrinkage which is less than 1%.

EXAMPLE 9 Dental Precomposition

(a) Eight grams of Ml of Example 8 are placed in an open cylindricalaluminum cup such that the volume occupied represents a thickness ofabout 6 mm.

The photocrosslinking of M1 and the calculation of the degree ofconversion of the epoxy functional groups are carried out according tothe methods described in Example 5.

The residual heat is 17 J/g relative to a noncrosslinked sample whichrepresents 237 J/g. Consequently, the effective degree of conversion ofthe epoxy functional groups with 0.1% of photoinitiator is therefore93%.

(b) The photocrosslinking and the calculation of the degree ofconversion of the epoxy functional groups are also carried out for acomposition M1 containing 5% w/w of a silicone oil of formula B₁ witha=12 on average.

The degree of conversion of the epoxy functional groups is 99% with aresidual heat of 1.5 J/g.

(c) The photocrosslinking and the calculation of the degree ofconversion of the epoxy functional groups are also carried out for acomposition Ml containing 5% w/w of a silicone oil with a=12 on averageand of formula:

The degree of conversion of the epoxy functional groups is 99% with aresidual heat of 0.1 J/g.

(d) The photocrosslinking and the calculation of the degree ofconversion of the epoxy functional groups are also carried out for acomposition M1 containing 5% by weight of siloxane resin of theMQM^(Epoxy) type containing 0.5% by weight of hydroxysilyl functionalgroups and 2% by weight of epoxy functional group (mass 43).

The degree of conversion of the epoxy functional groups is 99%.

EXAMPLE 10 Composition for Dental Prosthesis or Dental RestorationMaterial

The following are mixed using a three-blade stirrer:

-   -   100 parts of silicone (B),    -   62 ppm of photosensitizer (PS1),    -   0.5 part of photoinitiator (P1) at 10% in solution in silicone        (B),    -   and 120 parts of precipitated silica (ground quartz).

A mixture is obtained which is opaque, gray in color, nonflowing andcapable of being handled.

The crosslinking operation is carried out in a manner identical to thatof Example 2. A composition mm thick is crosslinked in less than 30seconds. The color of the material after crosslinking is similar toivory color.

The composition, in this case, is suitable in particular for dentalprostheses, in particular the stiffness is greater than 80 Mpa accordingto the ISO 1567 standard.

EXAMPLE 11 Dental Composition

The following are mixed using a three-blade stirrer:

-   -   95 parts of silicone (8) stabilized with 50 ppm of Tinuvin 765,    -   62 ppm of photosensitizer (PS1),    -   0.5 part of photoinitiator (21) at 10% in silicone (B),    -   5 parts of polydimethylsiloxane 81 where a=12 on average,    -   and 120 parts of precipitated silica (ground quartz).

The crosslinking operation is carried out in a manner identical to thatof Example 2. The measured stiffness values are greater than 80 Mpaaccording to the ISO 1567 standard.

1. A low shrinking polymerizable or crosslinkable composition for dentalprosthesis, dental restoration and temporary teeth comprising a mixtureof: (1) at least one crosslinkable and/or polymerizable siliconeoligomer or polymer which is liquid at room temperature or which isheat-meltable at a temperature of less than 100° C., and whichcomprises: at least one unit of formula (FS):Z—Si—(R⁰ _(a))—O_((3-a)/2) wherein: a=0, 1 or 2, R⁰, identical ordifferent, represents an alkyl, cycloalkyl, aryl, vinyl, hydrogeno oralkoxy radical, Z, identical or different, is an organic substituentcomprising at least one reactive epoxy, or alkenyl ether or oxetane ordioxolane or carbonate functional group, and at least two silicon atoms,(2) at least one aromatic hydrocarbon photosensitizer, having a residuallight absorption of between 200 and 500 nm, and selected from the groupconsisting of the following formulae (VIII), (X), (XII) and (XXII):thioxanthones of formula (VIII):

wherein: m=0 to 8, R¹⁷, which symbolizes identical or differentsubstituent(s) on the aromatic framework, represent a linear C₁-C₁₂alkyl radical, a branched C₁-C₁₂ alkyl radical, a C₆-C₁₂ cycloalkylradical, a radical Ar¹, a halogen atom, an —OH, —CN, —NO₂, —COOR⁶, —CHO,Ophenyl, —F₃, —SR⁶, -Sphenyl, —SO₂phenyl, Oalkenyl, or —SiR⁶ ₃ group;xanthones of formula (X):

wherein p=0 to 8 anthracene of formula (XII):

wherein r=0 to 10, and biscoumarins of formula (XXII):

wherein: R¹⁸, identical or different, has the same meaning as R¹⁷ aboveor represents a group: —NR⁶ ₂, wherein R₆ represents a linear C₁-C₁₂alkyl radical, (3) at least one dental filler present in a proportion ofat least 10% by weight relative to the total weight of the composition,and (4) an effective quantity of at least one borate-typephotoinitiator, whose anionic portion is selected from the groupconsisting of: 1′: [B(C₆F₅)₄]⁻ 2′: [(C₆F₅)₂BF₂]⁻ 3′: [B(C₆H₄CF₃)₄]⁻ 4′:[B(C₆F₄OCF₃)₄]³¹ 5′: [B(C₆H₃(CF₃)₂)₄]⁻ 6′: [B(C₆H₃F₂)₄]⁻ 7′: [C₆F₅BF₃]⁻and whose cationic portion is selected from the group consisting of:[(φ)₂I]⁺ [C₈H₁₇-O-φ-I-φ]⁺ [(φ-CH₃)₂ I]⁺ [C₁₂H₂₅-φ-I-φ]⁺ [(C₈H₁₇-O-φ)₂I]⁺ [(C₈H₁₇-O-φ-I-φ)]⁺ [(φ)₃ S]⁺ [(φ)₂-S-φ-O-C₈H₁₇]⁺ [(CH₃-φ-I-φ-CH₃)₂]⁺[φ-S-φ-S-(φ)₂]⁺ [(C₁₂H₂₅-φ)₂ I]⁺ [(CH₃-φ-I-φ-OC₂H₅]⁺(η⁵-cyclopentadienyl)(η⁶-toluene) Fe⁺,(η⁶-cyclopentadienyl)(η⁶-methyl-1-naphthalene) Fe⁺, and(η⁵-cyclopentadienyl)(η⁶-cumene) Fe⁺, and wherein the composition has avolumetric polymerization and/or crosslinking shrinkage of less than1.5% v/v.
 2. The dental composition as claimed in claim 1, wherein Z isan organic substituent Z1 comprising at least one reactive epoxy, ordioxolane functional group.
 3. The dental composition as claimed claim1, wherein the reactive functional group Z1 is:


4. The dental composition as claimed in claim 1, wherein thephotoinitiator is selected from the group consisting of: [(φ)₂ I]⁺,[B(C₆F₅)₄]⁻ [(C₈H₁₇)-O-φ-I-φ)]⁺, [B(C₆F₅)₄]⁻ [C₁₂H₂₅-φ-I-φ]⁺,[B(C₆F₅)₄]⁻ [(C₈H₁₇-O-φ)₂I]⁺, [B(C₆F₅)₄]⁻ [(C₈H₁₇)-O-φ-I-φ)]⁺,[B(C₆F₅)₄]⁻ [(φ)₃S]⁺, [B(C₆F₅)₄]⁻ [(φ)₂S-φ-O-C₈H₁₇]⁺, [B(C₆H₄CF₃)₄]⁻[(C₁₂H₂₅-φ)₂I]^(+, [B(C) ₆F₅)₄]⁻ [(φ)₃ S]⁺, [B(C₆F₄OCF₃)₄]⁻[(φ-CH₃)₂I]⁺, [B(C₆F₅)₄]⁻ [(φ-CH₃)₂ I]⁺, [B(C₆F₄OCF₃)₄]⁻[CH₃-φ-I-φCH(CH₃)₂]^(−, [B(C) ₆F₅)₄]⁻ (η⁵-cyclopentadienyl)(η⁶-toluene)Fe⁺, [B(C₆F₅)₄]⁻, (η⁵-cyclopentadienyl)(η⁶-methyl-1-naphthalene) Fe⁺,[B(C₆F₅)₄]⁻, and (η⁵-cyclopentadienyl)(η⁶-cumene) Fe⁺, [B(C₆F₅)₄]⁻. 5.The dental composition as claimed in claim 1, wherein thephotosensitizer of formula (XXII) is3,3′-carbonylbis(7-diethylaminocoumarin) or3,3′-carbonylbis(7-methoxycoumarin).
 6. The dental composition of claim1, wherein said composition has a Shore D hardness of at least about 50upon polymerization.
 7. The dental composition of claim 1, wherein saidcomposition has a Shore D hardness of at least about 80 uponpolymerization.